Pneumatic tires to be used with a four-wheel drive vehicle and the like are required to have good rock performance (or running performance on rocky ground) and good mud performance (or running performance on muddy ground). Hereinafter, these performances are comprehensively referred to as off-road performance.
On the other hand, a pneumatic tire which is, in order to improve the cut resistance of the sidewall portions, provided in the sidewall portions with axially outwardly protruding side protectors has been proposed. Such side protectors can exert tractional force by the engagement and friction between the side protectors and rocks on the rocky ground as well as by the shearing of the mud entered into reentrant portions formed between the side protectors. Thus, the off-road performance can be improved.
In order that the off-road performance and cut resistance performance are improved, if the side protectors are increased in the protruding height, then the tire sidewall portion is increased in the rubber volume in its radially outer region especially. Therefore, there are problems such that the weight of the tire is unfavorably increased, and the durability of the bead portion of the tire is deteriorated because the flexural stress of the sidewall portion concentrates in a region from the lower sidewall region to the bead portion.